U.S. patent number 6,775,920 [Application Number 10/437,911] was granted by the patent office on 2004-08-17 for method of fabricating semiconductor device comprising superposition inspection step.
This patent grant is currently assigned to Renesas Technology Corp.. Invention is credited to Shigenori Kido, Takeshi Kishida.
United States Patent |
6,775,920 |
Kishida , et al. |
August 17, 2004 |
Method of fabricating semiconductor device comprising superposition
inspection step
Abstract
A photolithography step is carried out for exposing/etching a
resist film in an etching step. Thereafter a superposition
inspection step employing a superposed layer superposition mark and
a resist film superposition mark is carried out with a
superposition inspection apparatus. In this step, an applied mask
confirmation step is simultaneously carried out with the
superposition inspection apparatus. Thus, it is possible to provide
a method of fabricating a semiconductor device including a
superposition inspection step, capable of efficiently confirming an
applied mask and improving the fabrication yield for the
semiconductor device.
Inventors: |
Kishida; Takeshi (Hyogo,
JP), Kido; Shigenori (Hyogo, JP) |
Assignee: |
Renesas Technology Corp.
(Tokyo, JP)
|
Family
ID: |
32708975 |
Appl.
No.: |
10/437,911 |
Filed: |
May 15, 2003 |
Foreign Application Priority Data
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Jan 10, 2003 [JP] |
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2003-004744 |
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Current U.S.
Class: |
33/645;
257/E23.179 |
Current CPC
Class: |
H01L
23/544 (20130101); G03F 7/70633 (20130101); H01L
2924/0002 (20130101); H01L 2223/54453 (20130101); H01L
2924/0002 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
G03F
7/20 (20060101); G01D 021/00 () |
Field of
Search: |
;33/645 ;355/43
;250/492 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
05-121284 |
|
May 1993 |
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JP |
|
09-266235 |
|
Oct 1997 |
|
JP |
|
08-298236 |
|
Nov 1998 |
|
JP |
|
Primary Examiner: Niebling; John F.
Assistant Examiner: Stevenson; Andre' C.
Attorney, Agent or Firm: McDermott Will & Emery LLP
Claims
What is claimed is:
1. A method of fabricating a semiconductor device including a
superposition inspection step for determining
properness/improperness of a superposed position of a resist film
formed on a superposed layer as a superpositive layer with a
superposition inspection apparatus, comprising: a step of reading
information of a superposed layer superposition mark provided on
said superposed layer; a step of reading information of a resist
film superposition mark provided on said resist film; a mark
position determination step of reading the positional relation
between said superposed layer superposition mark and said resist
film superposition mark from said information of said superposed
layer superposition mark and said information of said resist film
superposition mark and determining properness/improperness of the
position of formation of said resist film with respect to said
superposed layer; and a mark determination step of comparing said
information of said resist film superposition mark with information
of a registered resist film superposition mark previously
registered in said superposition inspection apparatus thereby
determining whether or not said resist film superposition mark
coincides with said registered resist film superposition mark.
2. The method of fabricating a semiconductor device including a
superposition inspection step according to claim 1, wherein said
step of reading said information of said superposed layer
superposition mark reads information of a mark formed on an etched
layer provided on said superposed layer to reflect the shape of
said superposed layer superposition mark.
3. The method of fabricating a semiconductor device including a
superposition inspection step according to claim 1, wherein said
information of said resist film superposition mark is information
based on the position of said resist film superposition mark.
4. The method of fabricating a semiconductor device including a
superposition inspection step according to claim 1, wherein said
information of said resist film superposition mark is information
based on the outer dimension of said resist film superposition
mark.
5. The method of fabricating a semiconductor device including a
superposition inspection step according to claim 1, wherein said
information of said resist film superposition mark is information
based on the pattern shape of said resist film superposition mark.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating a
semiconductor device, and more specifically, it relates to a method
of fabricating a semiconductor device including a superposition
inspection step for determining properness/improperness of
superposed positions of a superposed layer and a resist film
employed as a superpositive layer.
2. Description of the Background Art
In a process of fabricating a semiconductor device, a resist film
serving as a superpositive layer having a prescribed pattern is
provided on a prescribed layer (hereinafter referred to as a
superposed layer) for patterning the superposed layer, and employed
as a mask for etching the superposed layer or a layer interposed
between the superposed layer and the resist film. Therefore, it is
important to properly position the resist film with respect to the
superposed layer. Thus, it is also important to pattern the resist
film itself.
A method of positioning a resist film with respect to a superposed
layer 605 is briefly described with reference to FIGS. 12 to 17.
FIG. 12 is a plan view schematically showing the structure of a
photomask 500 for transferring prescribed patterns to the resist
film. The photomask 500 generally comprises wiring pattern regions
501 and 502 provided with wiring patterns for semiconductor devices
and a peripheral pattern region 510, enclosing the wiring pattern
regions 501 and 502, corresponding to a dicing line of a wafer.
The peripheral pattern region 510 is provided with a superposition
mark 530 employed for determining properness/improperness of
superposed positions of the superposed layer 605 and the resist
film.
Specific purposes of superposition marks are now briefly described.
FIG. 13 is a plan view of superposition marks formed on the
superposed layer 605 and the resist film respectively, and FIG. 14
is a sectional view taken along the line XIV--XIV in FIG. 13. An
etched layer 611 is provided with a superposed layer superposition
mark 611H formed to reflect the shapes of holes 605d provided on
the superposed layer 605 as superposed layer superposition marks,
while the resist film is provided with a resist film superposition
mark 701H transferred from the superposition mark 530 of the
aforementioned photomask 500.
A plurality of recesses 611h are arranged to form a square thereby
defining the overall shape of the superposed layer superposition
mark 611H, and the dimension (H) of one side of the square is about
25 .mu.m. When formed, the etched layer 611 partially drops into
the holes 605d provided in the superposed layer 605, thereby
forming the recesses 611h. The holes 605d are formed through the
same step as that of forming contact holes (not shown) in a wiring
region of the etched layer 611.
On the etched layer 611, the resist film superposition mark 701H
formed on the resist film is provided inside the superposed layer
superposition mark 611H. The dimension (h) of one side of the
resist film superposition mark 701H is about 10 .mu.m.
A general etching step 800 employing the superposition mark 611H
and 701H is now described with reference to FIG. 15. First, a
photolithography step is carried out for exposing/etching the
resist film (S810). Thereafter a superposition inspection step is
carried out with the superposed layer superposition mark 611H and
the resist film superposition mark 701H (S820).
In this superposition inspection step (S820), a superposition
inspection apparatus (not shown) is employed for reading the
positions of the superposed layer superposition mark 611H and the
resist film superposition mark 701h from image information of these
superposition marks 611H and 701h and determining whether or not
the resist film superposition mark 701H is present on a prescribed
position (tolerance position) of the superposed layer superposition
mark 611H.
If the resist film superposition mark 701H is present on the
prescribed position of the superposed layer superposition mark
611H, the superposition marks 611H and 701H are determined as
acceptable and the process makes a transition to a development
inspection step (S830). If the superposition marks 611H and 701H
are rejectable, the resist film is removed so that a new resist
film is applied and exposed/etched (S810).
Then, a resist dimension inspection step (S840) and an applied mask
confirmation step (S850) are carried out for thereafter executing
an etching step for the etched layer 611 through the resist film
(S860) and making a transition to a subsequent step (S870).
However, a method of fabricating a semiconductor device including
the aforementioned superposition inspection step has the following
problems:
In the process of fabricating a semiconductor device, different
photomasks may be employed in the same photolithography step due to
revision of the semiconductor device pattern, addition of a
type-oriented option or the like.
For example, FIG. 16 is a sectional view of a semiconductor device
including a first semiconductor layer 601 provided with conductive
regions 602, 603 and 604 and an interlayer dielectric film 605
having contact holes 605a, 605b and 605c reaching the conductive
regions 602, 603 and 604 respectively.
Contact plugs 607, 608 and 609 reaching the conductive regions 602,
603 and 604 are provided in the contact holes 605a, 605b and 605c
respectively. Further, a wiring layer 611A communicating with the
contact plug 607 and a wiring layer 611B communicating with the
contact plugs 608 and 609 are formed on the interlayer dielectric
film 605. The wiring layers 611A and 611B are patterned through a
resist film 701A having patterns corresponding to the wiring layers
611A and 611B.
FIG. 17 is a sectional view of another semiconductor device having
a basic structure identical to that of the aforementioned
semiconductor device shown in FIG. 16. The semiconductor device
shown in FIG. 17 is different from that shown in FIG. 16 in a point
that the same is provided with wiring layers 611C and 611D
communicating with contact plugs 608 and 609 respectively.
Therefore, these wiring layers 611C and 611D are patterned through
a resist film 701B having patterns corresponding to a wiring layer
611A and the wiring layers 611C and 611D.
Thus, regions X1 to X4 having partially different wiring structures
are interspersed as shown in the plan view of FIG. 12, for example,
and the difference between the wiring structures is confirmed in
the applied mask confirmation step (S850) carried out in the second
half of the etching step 800 shown in FIG. 15.
This is because all superposition marks are generally shaped
identically to each other and provided on identical positions of
peripheral pattern regions of photomasks having different patterns
and hence it is impossible to determine whether or not the applied
photomask 500 is correct in the steps S820 to S840 shown in FIG.
15. Thus, correctness of the applied photomask 500 is confirmed in
the second half of the etching step 800, leading to hindrance of
improvement of the working efficiency.
Further, the applied mask confirmation step (S850) is generally
manually carried out offline, leading to reduction of the
fabrication yield for the semiconductor device resulting from
overlook of incorrectness of the photomask 500.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of
fabricating a semiconductor device including a superposition
inspection step, capable of efficiently confirming an applied mask
and improving the fabrication yield for the semiconductor
device.
In order to attain the aforementioned object, the inventive method
of fabricating a semiconductor device including a superposition
inspection step for determining properness/improperness of a
superposed position of a resist film formed on a superposed layer
as a superpositive layer with a superposition inspection apparatus
comprises the following steps:
A first step is carried out for reading information of a superposed
layer superposition mark provided on the aforementioned superposed
layer. A second step is carried out for reading information of a
resist film superposition mark provided on the aforementioned
resist film.
Then, a mark position determination step is carried out for reading
the positional relation between the aforementioned superposed layer
superposition mark and the aforementioned resist film superposition
mark from the aforementioned information of the layer superposition
mark and the aforementioned information of the resist film
superposition mark, for determining properness/improperness of the
position of formation of the aforementioned resist film with
respect to the aforementioned superposed layer.
A mark determination step is carried out for comparing the
aforementioned information of the resist film superposition mark
with information of a registered resist film superposition mark
previously registered in the aforementioned superposition
inspection apparatus thereby determining whether or not the
aforementioned resist film superposition mark coincides with the
aforementioned registered resist film superposition mark.
The foregoing and other objects, features, aspects and advantages
of the present invention will become more apparent from the
following detailed description of the present invention when taken
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow chart showing an etching step for a semiconductor
device, to which a method of fabricating a semiconductor device
including a superposition inspection step according to a first
embodiment of the present invention is applied;
FIGS. 2 and 3 are plan views showing first and second superposition
mark regions in the first embodiment;
FIG. 4 is a flow chart showing the method of fabricating a
semiconductor device including a superposition inspection step
according to the first embodiment;
FIGS. 5 and 6 are plan views showing first and second superposition
mark regions in a method of fabricating a semiconductor device
including a superposition inspection step according to a second
embodiment of the present invention;
FIG. 7 is a flow chart showing the method of fabricating a
semiconductor device including a superposition inspection step
according to the second embodiment;
FIGS. 8 and 9 are plan views showing first and second superposition
mark regions in a method of fabricating a semiconductor device
including a superposition inspection step according to a third
embodiment of the present invention;
FIG. 10 is a flow chart showing the method of fabricating a
semiconductor device including a superposition inspection step
according to the third embodiment;
FIG. 11 is a sectional view showing the structure of a
semiconductor device in a further embodiment of the present
invention;
FIG. 12 is a plan view schematically showing the structure of a
conventional photomask for transferring prescribed patterns to a
resist film;
FIG. 13 is a plan view of superposition marks formed on an etched
layer and the resist film respectively;
FIG. 14 is a sectional view taken along the line XIV--XIV in FIG.
13;
FIG. 15 is a flow chart illustrating a general etching step
employing the superposition marks;
FIG. 16 is a first sectional view showing the structure of a
semiconductor device; and
FIG. 17 is a second sectional view showing the structure of another
semiconductor device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of a method of fabricating a semiconductor device
including a superposition inspection step according to the present
invention are now described with reference to FIGS. 1 to 11. Each
embodiment is illustrative and not restrictive in all points. In
each embodiment, the present invention is applied to a general
wiring structure applied to a semiconductor device. In other words,
the present invention is not restricted to a specific semiconductor
device but is widely applicable to general semiconductor
devices.
First Embodiment
A method of fabricating a semiconductor device including a
superposition inspection step according to a first embodiment of
the present invention is now described with reference to FIGS. 1 to
4.
Referring to FIG. 1, a photolithography step is first carried out
in the etching step 100 according to the first embodiment for
exposing/etching a resist film (S101). Thereafter a superposition
inspection step employing a superposed layer superposition mark and
a resist film superposition mark with a superposition inspection
apparatus (S102A). In this step, an applied mask confirmation step
is simultaneously carried out with the superposition inspection
apparatus (S102B). Thereafter a development inspection step (S103),
a resist dimension inspection step (S104) and an etching step
(S105) are carried out, for making a transition to a subsequent
step (S106).
Thus, the feature of the first embodiment resides in that the
applied mask confirmation step (S102B), manually carried out
offline after the resist dimension inspection step in the
conventional etching step 800 shown in FIG. 15, is carried out
simultaneously with the superposition inspection step with the
superposition inspection apparatus (S102A). A method of
simultaneously carrying out the superposition inspection step
(S102A) and the applied mask confirmation step (S102B) is now
described in detail.
Referring to FIGS. 2 and 3, the superposed layer is provided with a
first superposed layer superposition mark 611A and a second
superposed layer superposition mark 611b on prescribed positions
respectively. The number of the superposed layer superposition
marks 611A and 611B is properly selected. The first and second
superposed layer superposition marks 611A and 611B are identical in
shape etc. to the conventional superposed layer superposition mark
611H shown in FIGS. 13 and 14.
Referring to FIG. 2, a resist film superposition mark 701A
transferred to a resist layer through a photomask having a first
wiring pattern is provided inside the first superposed layer
superposition mark 611A. Referring to FIG. 3, another resist film
superposition mark 701b transferred to the resist layer through a
photomask having a second wiring pattern is provided inside the
second superposed layer superposition mark 611B. The resist film
superposition marks 701A and 701B are identical to the conventional
resist film superposition mark 701H shown in FIGS. 13 and 14.
The flow of the method of fabricating a semiconductor device
including the superposition inspection step (S102A) in a case of
etching an etched layer through the photomask having the first
wiring pattern according to the first embodiment is now described
with reference to FIG. 4.
First, the superposition inspection apparatus previously stores
data of the photomask having the first wiring pattern provided with
the resist film superposition mark 701A (S120). Thereafter the
superposition inspection apparatus loads and aligns a wafer (S121).
Thereafter the superposition inspection apparatus recognizes
superposition mark coordinates (S122).
Then, the superposition inspection apparatus reads information of
the superposed layer superposition marks 611A and 611B provided on
the superposed layer and information of the resist film
superposition mark 701A provided on the resist film (S123).
Then, the superposition inspection apparatus reads the positional
relation between the superposed layer superposition mark 611A and
the resist film superposition mark 701A from the information of the
superposed layer superposition marks 611A and 611B and the
information of the resist film superposition mark 701A, for
determining properness/improperness of the position of formation of
the resist film with respect to the superposed layer (S124).
Then, the superposition inspection apparatus compares the
information of the resist film superposition mark 701A with
information of a registered resist film superposition mark
previously registered therein at the step S120, thereby determining
whether or not the resist film superposition mark 701A coincides
with the registered resist film superposition mark (S125).
More specifically, the superposition inspection apparatus
determines the aforementioned properness/improperness by
determining whether or not the resist film superposition mark 701A
is present within the superposed layer superposition mark 611A.
When the photomask having the second wiring pattern provided with
the resist film superposition mark 701B shown in FIG. 3 is falsely
mounted on the superposition inspection apparatus, therefore, the
superposition inspection apparatus recognizes that no resist film
superposition mark 701A is present within the superposed layer
superposition mark 611A and informs an operator of the result.
In the method of fabricating a semiconductor device including a
superposition inspection step according to the first embodiment,
the mark determination step of determining whether or not the
resist film superposition mark coincides with the registered resist
film superposition mark is carried out simultaneously with the mark
position determination step of determining properness/improperness
of the position of formation of the resist film with respect to the
superposed layer, for improving the working efficiency by
determining whether or not the applied photomask is correct in an
early stage of the etching step. Further, correctness of the
applied photomask is determined not through a manual offline
operation but through the online operation employing the
superposition inspection apparatus, thereby enabling improvement of
the fabrication yield for the semiconductor device with no overlook
of false application of the photomask.
According to this embodiment, further, the information based on the
position of the resist film superposition mark is employed as the
information of the resist film superposition mark, thereby enabling
utilization of information employed for determining mark positions
in a conventional superposition inspection apparatus.
Second Embodiment
A method of fabricating a semiconductor device including a
superposition inspection step according to a second embodiment of
the present invention is now described with reference to FIGS. 5 to
7.
The method of fabricating a semiconductor device including a
superposition inspection step according to the second embodiment is
basically identical to the aforementioned method of fabricating a
semiconductor device including a superposition inspection step
according to the first embodiment, and hence only difference
between these methods is now described.
Referring to each of FIGS. 5 and 6, a superposed layer
superposition mark 611C is provided on a prescribed position of a
superposed layer. The superposed layer superposition mark 611C is
identical in dimension, shape etc. to the conventional superposed
layer superposition mark 611H shown in FIGS. 13 and 14.
Referring to FIG. 5, a resist film superposition mark 701C
transferred to a resist layer through a photomask having a first
wiring pattern is in the form of a square provided inside the
superposed layer superposition mark 611C, and the dimension (h) of
each side thereof is 10 .mu.m. Referring to FIG. 6, a resist film
superposition mark 701D transferred to the resist layer through a
photomask having a second wiring pattern is also in the form of a
square provided inside the superposed layer superposition mark
611C, and the dimension (h) of each side thereof is 17 .mu.m. The
resist film superposition marks 701C and 701D are identical in
shape to the conventional resist film superposition mark 701H shown
in FIGS. 13 and 14.
The flow of a superposition inspection step (S102A) for etching an
etched layer of a semiconductor device through the photomask having
the first wiring pattern according to this embodiment is now
described with reference to FIG. 7.
First, a superposition inspection apparatus previously stores data
of the photomask having the first wiring pattern provided with the
resist film superposition mark 701C (S120). Thereafter the
superposition inspection apparatus loads and aligns a wafer (S121).
Thereafter the superposition inspection apparatus recognizes
superposition mark coordinates (S122).
Then, the superposition inspection apparatus reads information of
the superposed layer superposition mark 611 provided on the
superposed layer and the information of the resist film
superposition mark 701C provided on a resist film (S123).
Then, the superposition inspection apparatus reads the positional
relation between the superposed layer superposition marks 611C and
the resist film superposition mark 701C from the information of the
superposed layer superposition marks 611C and that of the resist
film superposition mark 701C for determining
properness/improperness of the position of formation of the resist
film with respect to the superposed layer (S124).
Then, the superposition inspection apparatus compares the
information of the resist film superposition mark 701C with
information of a registered resist film superposition mark
previously registered therein at the step S120, thereby determining
whether or not the resist film superposition mark 701C coincides
with the registered resist film superposition mark (S125).
More specifically, the superposition inspection apparatus
determines whether or not the length of each side of the resist
film superposition mark 701C is 10 .mu.m. If the photomask having
the second wiring pattern provided with the resist film
superposition mark 701D shown in FIG. 6 is falsely mounted on the
superposition inspection apparatus, therefore, the superposition
inspection apparatus recognizes absence of the resist film
superposition mark 701C having the sides of 10 .mu.m in length, and
informs an operator of the result.
Also in the method of fabricating a semiconductor device including
a superposition inspection step according to the second embodiment,
the working efficiency can be improved by determining whether or
not the applied photomask is correct in an early stage of the
etching step, similarly to the aforementioned first embodiment.
Further, correctness of the applied photomask is determined not
through a manual offline operation but through the online operation
employing the superposition inspection apparatus, thereby enabling
improvement of the fabrication yield for the semiconductor device
with no overlook of false application of the photomask.
According to this embodiment, further, the information based on the
length of each side, i.e., the outside dimension of the resist film
superposition mark is employed as the information of the resist
film superposition mark, thereby enabling utilization of
information employed for determining mark positions in the
conventional superposition inspection apparatus.
Third Embodiment
A method of fabricating a semiconductor device including a
superposition inspection step according to a third embodiment of
the present invention is now described with reference to FIGS. 8 to
10.
The method of fabricating a semiconductor device including a
superposition inspection step according to the third embodiment is
basically identical to the aforementioned method of fabricating a
semiconductor device including a superposition inspection step
according to the first embodiment, and hence only difference
between these methods is now described.
Referring to each of FIGS. 8 and 9, a superposed layer
superposition mark 611D is provided on a prescribed position of a
superposed layer. The superposed layer superposition mark 611D is
identical in dimension, shape etc. to the conventional superposed
layer superposition mark 611H shown in FIGS. 13 and 14.
Referring to FIG. 8, a resist film superposition mark 701E
transferred to a resist layer through a photomask having a first
wiring pattern is in the form of a square provided inside the
superposed layer superposition mark 611D with a dimension (h) of 10
.mu.m of each side, and linearly patterned similarly to the
conventional resist film superposition mark 701H shown in FIGS. 13
and 14.
Referring to FIG. 9, a resist film superposition mark 701F
transferred to the resist layer through a photomask having a second
wiring pattern is also in the form of a square provided inside the
superposed layer superposition mark 611D with a dimension (h) of 10
.mu.m of each side, while the same is formed by a plurality of
recesses 701f.
The flow of the method of fabricating a semiconductor device
including a superposition inspection step (S102A) in a case of
etching an etched layer of a semiconductor device through the
photomask having the first wiring pattern according to this
embodiment is now described with reference to FIG. 10.
First, a superposition inspection apparatus previously stores data
of the photomask having the first wiring pattern provided with the
resist film superposition mark 701E (S120). Thereafter the
superposition inspection apparatus loads and aligns a wafer (S121).
Thereafter the superposition inspection apparatus recognizes
superposition mark coordinates (S122).
Then, the superposition inspection apparatus reads information of
the superposed layer superposition mark 611D provided on the
superposed layer and the information of the resist film
superposition mark 701E provided on a resist film (S123).
Then, the superposition inspection apparatus reads the positional
relation between the superposed layer superposition mark 611D and
the resist film superposition mark 701E from the information of the
superposed layer superposition mark 611D and that of the resist
film superposition mark 701E for determining
properness/improperness of the position of formation of the resist
film with respect to the superposed layer (S124).
Then, the superposition inspection apparatus compares the
information of the resist film superposition mark 701E with
information of a registered resist film superposition mark
previously registered therein at the step S120, thereby determining
whether or not the resist film superposition mark 701E coincides
with the registered resist film superposition mark (S125).
More specifically, the superposition inspection apparatus
determines whether or not the resist film superposition mark 701E
is linearly patterned. If the photomask having the second wiring
pattern provided with the resist film superposition mark 701F shown
in FIG. 9 is falsely mounted on the superposition inspection
apparatus, therefore, the superposition inspection apparatus
recognizes absence of the linearly patterned resist film
superposition mark 701E, and informs an operator of the result.
Also in the method of fabricating a semiconductor device including
a superposition inspection step according to the third embodiment,
the working efficiency can be improved by determining whether or
not the applied photomask is correct in an early stage of the
etching step. Further, correctness of the applied photomask is
determined not through a manual offline operation but through the
online operation employing the superposition inspection apparatus,
thereby enabling improvement of the fabrication yield for the
semiconductor device with no overlook of false application of the
photomask.
According to this embodiment, further, the information based on the
pattern shape of the resist film superposition mark is employed as
the information of the resist film superposition mark, thereby
enabling utilization of information employed for determining mark
positions in the conventional superposition inspection
apparatus.
While the superposition inspection apparatus reads the information
of the mark formed on the etched layer provided on the superposed
layer to reflect the shape of the superposed layer superposition
mark formed on the superposed layer in each of the aforementioned
embodiments, the present invention is not restricted to this but is
also applicable to a step of fabricating a semiconductor device
shown in FIG. 11, for example.
This semiconductor device comprises superposed layer superposition
marks 802 provided on a substrate 801 in correspondence to bit
lines serving as superposed layers, an interlayer dielectric film
803 formed on the superposed layer superposition marks 802 as an
etched layer and a resist film 805 having resist film superposition
marks 804 formed on the interlayer dielectric film 803, with no
superposed layer superposition marks provided on the etched layer
dissimilarly to the structures shown in the aforementioned
embodiments.
In the method of fabricating a semiconductor device including a
superposition inspection step according to the present invention,
the working efficiency can be improved by determining whether or
not the applied photomask is correct in an early stage of the
etching step. Further, correctness of the applied photomask is
determined through the online operation employing the superposition
inspection apparatus, thereby enabling improvement of the
fabrication yield for the semiconductor device with no overlook of
false application of the photomask.
Although the present invention has been described and illustrated
in detail, it is clearly understood that the same is by way of
illustration and example only and is not to be taken by way of
limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
* * * * *